1. Field of the Invention
The present invention relates to a portable handset, and more particularly to a method for acquiring necessary information by using the portable handset.
2. Description of the Related Art
Together with the developments of communications technologies, portable handsets have been developed. The portable handsets acquire information stored in a specific server in addition to communications with different portable handsets. However, diverse additional functions have been developed to meet the needs of users using the portable handsets. Hereinafter, description will be made on a general structure of the portable handsets, and then description will be made on various additional functions of the portable handsets.
FIG. 1 is a view for showing a structure of a signal reception part of a general portable handset. Hereinafter, description will be made in detail on a structure of a signal reception part of the portable handset with reference to FIG. 1. An antenna 100 receives electromagnetic wave signals in the air, and then sends the signals to a band select filter (RSF) 102. The signals received by the antenna 100 has a signal that a user wants but includes other signals, so the band select filter 102 applies the bandpass filtering to enable only a user-desired frequency band to be amplified. In case plural wireless channels are used, it is necessary to pass the plural wireless channels, and, in case the same antenna is used, a duplexer performs the function of the band select filter 102.
A low noise amplifier (LNA) 104 prevents noise included in the received signal from being amplified, as well as amplifies the received signal. An image reject filter (IRF) 106 applies the bandpass filtering again not to send to a mixer an image that has to be removed out of the received signal amplified in the low noise amplifier 104. The received signal to which the bandpass filtering has been applied in the image reject filter 106 is sent to an RF down mixer 108.
An RF local oscillator 110 supplies a signal having an LO frequency to the RF down mixer 108 to mix frequencies. If a channel is necessarily selected, the channel can be selected as the LO frequency varies. A phase-locked loop (PLL) 112 fixes an output frequency of the RF local oscillator 110 to a certain frequency to prevent the output frequency from varying. The RF down mixer 108 uses the output frequency of the RF local oscillator 110 to convert an RF signal received from the image reject filter 106 into a frequency of an intermediate frequency (IF) band.
A channel select filter (CSF) 114 performs a function of applying the bandpass filtering to the IF frequency-converted signal to select only a desired channel. The channel select filter 114 has short intervals between channels, so it needs an excellent performance. An IF amplifier (IFA) 116 amplifies a filtered signal of a selected channel. The signal amplified in the IF amplifier 116 is sent to an IF down mixer 118. An IF local oscillator 120 sends an LO frequency to the IF down mixer 118 in order to convert the IF signal to a baseband signal. The phase-locked loop may be used to lock the LO frequency. The IF down mixer 118 uses the LO frequency to convert a signal of the IF band to a baseband signal, and outputs the converted baseband signal.
FIG. 2 is a view for showing a structure of a signal transmission part of a portable handset. Hereinafter, description will be made on a structure of a signal transmission part of the portable handset according to an embodiment of the present invention with reference to FIG. 2. The structure of the signal transmission part of the portable handset of FIG. 2 is similar to the structure of the signal reception part of the portable handset of FIG. 1. Thus, the description will be skipped when the structure is the same as that of the signal reception part of the portable handset.
The units from IF down mixer 200 to the image reject filter 214 operate reverse to the operations carried out in the units from the IF down mixer 118 to the image reject filter 106 that are shown in FIG. 1. Hereinafter, description will be made on the drive amplifier (DA) 216. The signal transmission part has a certain input signal unlike the signal reception part. The drive amplifier 216 solves the problem of the insufficient gain of the power amplifier 220, and performs a function of generating enough input power to the power amplifier 220. The band select filter 218 performs a function of removing unnecessary frequency output components out of the signals outputted from the drive amplifier 216. The power amplifier 220 amplifies power so that a signal having enough power at the final stage can be wirelessly transmitted. The isolator 222 performs a function of setting a signal direction in order for a signal to be sent in a specific direction. That is, the isolator 222 carries out a function of passing a signal in an output direction and removing a signal coming in a reverse direction. Thus, the signal coming in the reverse direction through the antenna 226 is removed. The band select filter 224 carries out the same function as the band select filter 102. That is, the band select filter 224 applies the last bandpass filtering in order to wirelessly pass only a desired frequency band. The transmission signal to which the bandpass filtering is applied is transmitted wirelessly through the antenna 226.
Hereinafter, description will be made on the radio frequency identification (RFID) that is used in various devices or units including portable handsets. The RFID technology has been developed to cope with the changed production method, changed consumer trends, advanced culture and technologies, and necessity of overcoming drawbacks of bar codes and magnetic cards. The RFID is a kind of contactless card, and contactless cards are generally referred to as RFID.
The RFID is characterized in that it does not need time for a user to insert it into readers, undergoes no friction or damage due to having no mechanical contacts, and has less pollution or environment influence. The antenna is continuously transmitting electromagnetic waves, and, if a card (TAG) in which ID and data are stored is in a range of the electromagnetic waves, the card sends to the antenna the ID and data the card itself holds. The antenna converts into a data signal the ID sent from the card, and sends the data signal to a personal computer (PC), and the personal computer performs a comparison with a database (DB) that has been stored, and provides desired services. Signal frequencies used at this time range from 10 kHz to 300 GHz, but a low frequency of 134.2 kHz is primarily used. Hereinafter, description will be made on the features of the RFID.
First, the RFID can recognize plural cards at the same time and at a high speed, to thereby saving time. Due to the above advantages, the RFID tag is replacing the bar code or the magnetic strip in the logistics field. Second, since the RFID has a long sensing distance, the RFID can be easily and widely applied depending on the system characteristics and peripheral environments. The RFID is also replacing the contact smart cards used for existing parking control systems. Third, the RFID has an excellent environment resistance, so it has a long life span. Since users do not have to insert the card into a reader and the card has no mechanical contact, the RFID has a very low error rate even under bad conditions such as card (TAG) damages due to friction, dust, humidity, temperature, snowfall, rainfall, and so on. Thus, the RFID is often applied to a system in an open area. Fourth, the RFID can pass through non-metal materials. Fifth, the RFID can recognize an object moving at a high speed. Since the time it takes from electric wave transmissions of the antenna to ID recognition is merely 0.01˜0.1 seconds, the RFID can be installed in and applied to a non-stop parking control system and automatic fare collection systems at non-stop highways or tunnels. Thanks to the above advantages, the RFID technology is being applied even to portable handsets, so diverse RFID technology application methods are being discussed.